Controls for windscreen wiper washing systems are known from the automotive and rail vehicle sectors. In the area of urban rail systems or LRVs (LRV=Light Rail Vehicle), such as on the tramways and metro, the vehicle is supplied with power from 24 V batteries with a rated voltage of 24 V, plus the usual tolerances. In this vehicle segment, windscreen wiper motors with a rotating direction of movement and downstream lever kinematics are used with preference. These motors generally have two basic speeds, the choice of speed being made by way of a further carbon brush that is arranged offset on the circumference of the commutator. These motors also have a device referred to as a “parking plate”, by which a parking position in the form of an opening contact on the circumference can be moved to. The DC motors available for industrial applications are not suitable for the application as a windscreen wiper drive if at least two speeds are required.
In the case of electrical multiple units, diesel-operated railcars or high-speed trains, the battery voltage is generally more than 24 V. Typical voltages in the case of the rail vehicles mentioned are 72 V, 96 V and 110 V DC. In order to make industrial motors suitable for the application as a windscreen wiper drive, a special control unit with a controllable voltage output is required.
In the case of the windscreen wiper drives used in the automotive sector, the only position detection is by the “parking plate” in the parking position. If the wiper arm is hindered in the course of movement, a defect to the windscreen wiper drive can only be prevented by thermal monitoring in the motor or sensing and monitoring of the motor current.
Windscreen wiper drives for use in the area of urban rail systems or LRVs (LRV—light rail vehicle) preferably consist of special windscreen wiper motors with three electrical connection points. This third brush, which is mounted offset on the circumference, allows part of the armature winding of the permanently excited motor to remain deenergized. As a result, a lower rotational speed is obtained at the motor. The rotational turning movement of the motor is converted by lever kinematics into a wiping movement. These motors generally have what is known as a “parking plate”, with which a switch is opened in a specially designated position of the drive output. The “parking plate” consists of at least one switching contact and a conductor track area on an insulating plate moving with the drive. This conductor track area is interrupted at one or more locations. If this interruption takes place during the operation of the drive, the electrical contact opens and the drive can consequently be switched off in the parking position. The activation of the speed stages takes place by an operator switch. Interval functions are realized by their own timer assemblies (for example: time-lag relays).
Disk-rotor motors with a reversing drive, which have a motor controller of their own on the drive, are also known from the automotive sector. The operating preselection is made here in the form of a digital, analog or digitally coded signal as “slow wiping” or “fast wiping”.